/*
 * This file is free software: you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This file is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
/*
  bouncebuffer code for DMA safe memory operations
 */
#include "stm32_util.h"
#include <stdint.h>
#include <string.h>
#include <stdio.h>
#include "bouncebuffer.h"

// Enable when trying to check if you are not just listening yourself
#define ENABLE_ECHO_SAFE 0

/*
  initialise a bouncebuffer
 */
void bouncebuffer_init(struct bouncebuffer_t **bouncebuffer, uint32_t prealloc_bytes, bool axi_sram)
{
    (*bouncebuffer) = calloc(1, sizeof(struct bouncebuffer_t));
    osalDbgAssert(((*bouncebuffer) != NULL), "bouncebuffer init");
    (*bouncebuffer)->on_axi_sram = axi_sram;
    if (prealloc_bytes) {
        (*bouncebuffer)->dma_buf = axi_sram?malloc_axi_sram(prealloc_bytes):malloc_dma(prealloc_bytes);
        if ((*bouncebuffer)->dma_buf) {
            (*bouncebuffer)->size = prealloc_bytes;
        }
    }
}

/*
  setup for reading from a device into memory, allocating a bouncebuffer if needed
  Note that *buf can be NULL, in which case we allocate DMA capable memory, but don't
  copy to it in bouncebuffer_finish_read(). This avoids DMA failures in dummyrx in the SPI LLD
 */
bool bouncebuffer_setup_read(struct bouncebuffer_t *bouncebuffer, uint8_t **buf, uint32_t size)
{
    if (!bouncebuffer || mem_is_dma_safe(*buf, size, bouncebuffer->on_axi_sram)) {
#if defined(STM32H7)
        // invalidate buffer so we know state in bouncebuffer_finish_read
        stm32_cacheBufferInvalidate(*buf, (size+31)&~31);
#endif
        return true;
    }
    osalDbgAssert((bouncebuffer->busy == false), "bouncebuffer read");        
    bouncebuffer->orig_buf = *buf;
    if (bouncebuffer->size < size) {
        if (bouncebuffer->size > 0) {
            free(bouncebuffer->dma_buf);
        }
        bouncebuffer->dma_buf = bouncebuffer->on_axi_sram?malloc_axi_sram(size):malloc_dma(size);
        if (!bouncebuffer->dma_buf) {
            bouncebuffer->size = 0;
            return false;
        }
        bouncebuffer->size = size;
    }
    *buf = bouncebuffer->dma_buf;
#if ENABLE_ECHO_SAFE
    memset(bouncebuffer->dma_buf, 0xBB, bouncebuffer->size);
#endif
#if defined(STM32H7)
    osalDbgAssert((((uint32_t)*buf)&31) == 0, "bouncebuffer read align");
    // invalidate buffer so we know state in bouncebuffer_finish_read
    stm32_cacheBufferInvalidate(*buf, (size+31)&~31);
#endif
    bouncebuffer->busy = true;
    return true;
}

/*
  finish a read operation
 */
void bouncebuffer_finish_read(struct bouncebuffer_t *bouncebuffer, const uint8_t *buf, uint32_t size)
{
#if defined(STM32H7)
    // clean+invalidate buffer after DMA transfer to it completed. invalidation
    // is mandatory as prefetch etc. could have re-cached it before completion.
    // clean is necessary as a bouncebuffer is sometimes used for non-DMA reads
    // and if we didn't clean first we would lose CPU-written data. there is no
    // risk of writing pre-DMA data as we invalidated any cached data before
    // starting, so it can only be dirty if the CPU dirtied it storing reads to
    // the bouncebuffer. in this case invalidation is unnecessary as no DMA
    // occurred, but we can't know which we need to do here, so we do both.
    stm32_cacheBufferFlush(buf, (size+31)&~31);
#endif

    if (bouncebuffer && buf == bouncebuffer->dma_buf) {
        osalDbgAssert((bouncebuffer->busy == true), "bouncebuffer finish_read");
        if (bouncebuffer->orig_buf) {
            memcpy(bouncebuffer->orig_buf, buf, size);
        }
        bouncebuffer->busy = false;
    }
}


/*
  setup for reading from memory to a device, allocating a bouncebuffer if needed
 */
bool bouncebuffer_setup_write(struct bouncebuffer_t *bouncebuffer, const uint8_t **buf, uint32_t size)
{
    if (!bouncebuffer || mem_is_dma_safe(*buf, size, bouncebuffer->on_axi_sram)) {
#if defined(STM32H7)
        /*
          on H7 we need to flush any pending writes to memory before the DMA operation
         */
        stm32_cacheBufferFlush(*buf, (size+31)&~31);
#endif
        return true;
    }
    osalDbgAssert((bouncebuffer->busy == false), "bouncebuffer write");        
    if (bouncebuffer->size < size) {
        if (bouncebuffer->size > 0) {
            free(bouncebuffer->dma_buf);
        }
        bouncebuffer->dma_buf = bouncebuffer->on_axi_sram?malloc_axi_sram(size):malloc_dma(size);
        if (!bouncebuffer->dma_buf) {
            bouncebuffer->size = 0;
            return false;
        }
        bouncebuffer->size = size;
    }
    if (*buf) {
        memcpy(bouncebuffer->dma_buf, *buf, size);
    }
    *buf = bouncebuffer->dma_buf;
#if defined(STM32H7)
    osalDbgAssert((((uint32_t)*buf)&31) == 0, "bouncebuffer write align");
    stm32_cacheBufferFlush(*buf, (size+31)&~31);
#endif
    bouncebuffer->busy = true;
    return true;
}


/*
  finish a write operation
 */
void bouncebuffer_finish_write(struct bouncebuffer_t *bouncebuffer, const uint8_t *buf)
{
    if (bouncebuffer && buf == bouncebuffer->dma_buf) {
        osalDbgAssert((bouncebuffer->busy == true), "bouncebuffer finish_wite");        
        bouncebuffer->busy = false;
    }
}

/*
  abort an operation
 */
void bouncebuffer_abort(struct bouncebuffer_t *bouncebuffer)
{
    if (bouncebuffer) {
        bouncebuffer->busy = false;
    }
}
